The present invention relates to fault monitoring circuits in general and, in particular, to fault monitoring circuits for light emitting diodes.
Light emitting diodes (“LEDs”) represent a fast growing market, at least because of their relatively high efficiency, low cost, and simplicity of handling and integration for many purposes. For example, LEDs may be found in numerous lighting applications, including automotive tail lamps and turn signals, large multicolor displays, flashlights, indicators, etc. In many of these applications, it may be undesirable to use a single LED (e.g., a single LED may not produce enough light). As such, multiple LEDs may be used in series.
Because of aging of the LEDs, undesirable power conditions, lead failures, and/or other reasons, some or all of the LEDs in a series application may fail. This failure may create either an open circuit at the LED or a short circuit at the LED. If the LED failure creates a short circuit, the other LEDs in series may still operate. If the LED failure creates an open circuit, the entire series string of LEDs may cease to operate (i.e., the open circuit may prevent current from flowing through the entire LED string). In either case, it may be desirable to detect and report the LED failure.
As such, it may be desirable to provide methods, systems, and devices for monitoring and reporting the failure of one or more LEDs in a series string of LEDs.